Originally published in 1941, the book has never been out of print since. Authors H. A. Rey and his wife Margret, creative partners who fled Europe during the Nazi occupation and settled in Cambridge, Massachusetts, wrote the original seven Curious George tales. In 1998 Houghton-Mifflin began publishing new Curious George adventures and continues to release new titles and formats. Curious George titles have sold more than 30 million copies worldwide and have been published in 17 languages, making the little monkey who left the jungle with The Man with the Yellow Hat one of the best-selling and most enduring characters in children's literature.